The present invention relates to an apparatus and a method for calibrating a reflective lens, and more particularly to an apparatus and method for calibrating a reflective lens for being used in manufacturing an image scanning apparatus.
As one of the peripheral equipment of a personal computer, the image scanner has become quite popular among computer users. The manufacturers of image scanners devoted themselves to improving the shortcoming and function of each component. Among the components of an image scanner, a reflective lens set is used to direct the image light beam of a scanning spot to a mirror set, and to focus on a charge coupled device (CCD) for being sensed. The reflective lens set, the mirror set and the CCD are commonly arranged inside a carriage. Because of the deviation of the lens 11 in a reflective lens set (please refer to FIGS. 1(a) and 1(b) respectively showing the deviation caused by rotational displacements of the lens 11 and FIG. 1(c) showing the deviation caused by a translational displacement of the lens 11), it results in a shift or deflection of the actual scanning line constructed by the reflective light path. The various errors on the scanning lines due to the inappropriate placement of lenses in a reflective lens set are shown in FIGS. 2(a)xcx9c2(d).
FIG. 2(a) shows an error in the X-direction (where X-direction is parallel to the direction of the scanning line) due to the inappropriate placement of a lens in a reflective lens set. The error causes a change in the scanning scope (X-direction) which results in a part of a scanned document being beyond the scanning window so that the image of that part can not be obtained. It also results in that the distance between the left end of the scanning line and the CCD is different from the optical distance between the right end of the scanning line and the CCD. It further affects the depth of view and the resolution of a scanning image.
FIG. 2(b) shows an error in the Y-direction (where Y-direction is parallel to the moving direction of the carriage) due to the inappropriate placement of a lens in a reflective lens set. The error causes a shift of the scanning spot in the Y-direction, resulting in a change in its optical distance. Moreover as the scanning spot shifts to the edge of or outside the transparent slot, a chromatic aberration phenomenon will be occurred to affect the scanning process.
FIG. 2(c) shows an error in both X-direction and Y-direction due to the inappropriate placement of a lens in a reflective lens set. The error causes a shift of the scanning spot in the X and Y directions simultaneously resulting in a change in its optical distance and a distortion of the scanning image. The change in the optical distance further affects the depth of view and the resolution of the scanning image. FIG. 2(d) shows an error in the light path due to the inappropriate placement of a lens in a reflective lens set. The deflected scanning line and the original scanning line will intersect at a right scanning position at a certain scanning height h1; however, a change in an optical distance and a chromatic aberration phenomenon may be occurred due to part of the light in the light path being blocked.
The above-mentioned deviation phenomenon is frequently appeared in the step of developing various parts of an image scanner during performing a verification process after mock-up or injection molding. It seriously affects the scanning quality and must be corrected by a calibrating apparatus and method after finding out the deviation factor Taiwanese Patent No. 325554 has disclosed a method for calibrating an assembling reflective lens of the linear scanning device. However, that calibrating method is relatively complicated. As the number of the reflective lenses in a reflective lens set increases, it requires the fabrication tools with higher precision for that calibrating method. Besides, the prior method performs an observation of the calibration at the location of a CCD and results in low accuracy because only a scale-down image is observed at the location of a CCD.
Thus, it is tried by the applicant to deal with the situation encountered with the prior art.
The object of the present invention is to provide an apparatus and a method for calibrating the various errors of a reflective lens on a carriage for being used in manufacturing an image scanning apparatus.
According to one aspect of the present invention, the apparatus adapted to be used in manufacturing an image scanning apparatus for calibrating a reflective lens on a carriage includes a fixing unit for fixing thereon the carriage, three point light sources located at three lined-up positions respectively, for respectively emitting point light beams to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and pass out of the carriage from one end thereof, and a calibrating device having thereon at a first distance from the end of the carriage a first set of three projective points from the three point light beams passing out of the end of the carriage and a first set of three calibrating points corresponding to the three point light sources and at a second distance from the end of the carriage a second set of three projective points from the three point light beams passing out of the end of the carriage and a second set of three calibrating points corresponding to the three point light sources for matching each of the projective points on the calibrating device with a corresponding one of the calibrating points by adjusting an angle and a position of the reflective lens on the carriage so as to achieve a calibrating function.
In a preferred embodiment, the three lined-up positions are located over which an image sensing device of the image scanning apparatus is to travel.
In another preferred embodiment, the three lined-up positions are located to which the light paths of the image scanning apparatus are to extend. Preferably, the three point light sources are laser light sources.
Preferably, the calibrating device includes a first calibrating plate located at the first distance from the end of the carriage for obtaining thereon the first set of three projective points and the first set of three calibrating points and a second calibrating plate located at the second distance from the end of the carriage for obtaining thereon the second set of three projective points and the second set of three calibrating points.
Preferably, the first calibrating plate and the second calibrating plate are made of transparent material.
Preferably, the end of the carriage is provided for accommodating an object to be scanned.
In accordance with another aspect of the present invention, the method of calibrating a reflective lens on a carriage for being used in manufacturing an image scanning apparatus includes the steps of (a) fixing the carriage to a certain position, (b) installing three point light sources on three lined-up positions respectively, (c) at a first distance from one end of the carriage defining a first set of three calibrating points with respect to the three point light sources, (d) at a second distance from the end of the carriage, defining a second set of three calibrating points with respect to the three point light sources, (e) causing each of the three point light sources to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and passing out from the end of the carriage so as to obtain a first set of three projective points and a second set of three projective points, and (f) adjusting an angle and a position of the reflective lens on the carriage for matching each of the projective points with a corresponding one of the calibrating points so as to achieve a calibrating function.
In a preferred embodiment, the first set of three projective points and the first set of three calibrating points are disposed on a first calibrating plate located at a first distance from the end of the carriage.
In another preferred embodiment, the second set of three projective points and the second set of three calibrating points are disposed on a second calibrating plate located at a second distance from the end of the carriage.
In accordance with another aspect of the present invention, the apparatus adapted to be used in manufacturing an image scanning apparatus for calibrating a reflective lens on a carriage includes a fixing unit for fixing thereon the carriage, a movable point light source located at three lined-up positions alternately, for alternately emitting a point light beam from each of the three lined-up positions to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and pass out of the carriage from one end thereof, a first calibrating piece located at a first distance from the end of the carriage for obtaining thereon a first set of three projective points from the three point light beams passing out of the end of the carriage and having thereon a first set of three calibrating points corresponding to the three light beams from the three lined-up positions, and a second calibrating piece located at a second distance from the end of the carriage for obtaining thereon a second set of three projective points from the three point light beams passing out of the end of the carriage and having thereon a second set of three calibrating points corresponding to the three point light beams from the three lined-up positions for matching each of the projective points on the calibrating pieces with a corresponding one of the calibrating points by adjusting an angle and a position of the reflective lens on the carriage so as to achieve a calibrating function.
In a preferred embodiment, the point light source is a laser light source.
In another preferred embodiment, both calibrating pieces are in a form of plate and are made of transparent material.
In accordance with another aspect of the present invention, the method of calibrating a reflective lens on a carriage for being used in manufacturing an image scanning apparatus includes the steps of (a) fixing the carriage to a certain position, (b) installing a movable point light source on each of three lined-up positions alternately, for alternately emitting three point light beams from the three lined-up positions, (c) at a first distance from one end of the carriage, defining a first set of three calibrating points with respect to the three point light beams from the three lined-up positions, (d) at a second distance from the end of the carriage, defining a second set of three calibrating points with respect to the three point light beams from the three lined-up positions, (e) causing each of the point light beams to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and pass out from the end of the carriage so as to obtain a first set of three projective points and a second set of three projective points, and (f) adjusting an angle and a position of the reflective lens on the carriage for matching each of the projective points with a corresponding one of the calibrating points so as to achieve a calibrating function.
In accordance with another aspect of the present invention, the apparatus adapted to be used in manufacturing an image scanning apparatus for calibrating a reflective lens on a carriage includes a fixing unit for fixing thereon the carriage, a point light source located at a position for emitting point light beam to transmit along a predetermined light path of the image scanning apparatus into the carriage and pass out of the carriage from one end thereof, and a calibrating device having thereon at a first distance from the end of the carriage a first projective point from the point light beam passing out of the end of the carriage and a first calibrating point corresponding to the point light source, the calibrating device having thereon at a second distance from the end of the carriage a second projective point from the point light beam passing out of the end of the carriage and a second calibrating point corresponding to the point light source for matching each of the projective points on the calibrating device with a corresponding one of the calibrating points by adjusting an angle and a position of the reflective lens on the carriage so as to achieve a calibrating function.
In a preferred embodiment, the calibrating device includes a first calibrating plate located at the first distance from the end of the carriage for obtaining thereon the first projective point from the light beam passing out of the end of the carriage and having thereon the first calibrating point corresponding to the light source, and a second calibrating plate located at the second distance from the end of the carriage for obtaining thereon the second projective point from the light beam passing out of the end of the carriage and having thereon the second calibrating point corresponding to the light source.
In accordance with another aspect of the present invention, the method of calibrating a reflective lens on a carriage for being used in manufacturing an image scanning apparatus includes the steps of (a) fixing the carriage to a certain position, (b) installing a point light source on a specific position, (c) at a first distance from one end of the carriage, defining a first calibrating point with respect to the point light source, (d) at a second distance from the end of the carriage, defining a second calibrating point with respect to the point light source, (e) causing the point light source to transmit along a predetermined light path of the image scanning apparatus into the carriage and pass out from the end of the carriage so as to obtain a first projective point and a second projective point, and (f) adjusting an angle and a position of the reflective lens on the carriage for matching each of the projective points with a corresponding one of the calibrating points so as to achieve a calibrating function.
In a preferred embodiment, the specific position is located over which an image sensing device of the image scanning apparatus is to travel.
In another preferred embodiment, the specific position is located to which the predetermined light path of the image scanning apparatus is to extend.
In accordance with another aspect of the present invention, the apparatus adapted to be used in manufacturing an image scanning apparatus for calibrating a reflective lens on a carriage includes a fixing unit for fixing thereon the carriage, two point light sources located at two specific positions respectively, for respectively emitting point light beams to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and pass out of the carriage from one end thereof, a first calibrating piece located at a first distance from the end of the carriage for obtaining thereon a first set of two projective points, wherein a third projective point lined up with the first set of two projective points is obtained by operating the first set of two projective points to develop a first set of three projective points and to define a first set of three calibrating points on the first calibrating piece to be compared to the first set of three projective points and a second calibrating piece located at a second distance from the end of the carriage for obtaining thereon a second set of two projective points, wherein another third projective point lined up with the second set of two projective points is obtained by operating the second set of two projective points to develop a second set of three projective points and to define a second set of three calibrating points on the second calibrating piece to be compared to the second set of three projective points for matching each of the projective points on the calibrating pieces with a corresponding one of the calibrating points by adjusting an angle and a position of the reflective lens on the carriage so as to achieve a calibrating function.
In accordance with another aspect of the present invention, the method of calibrating a reflective lens on a carriage for being used in manufacturing an image scanning apparatus includes the steps of (a) fixing thereon the carriage to a certain position, (b) installing two point light sources on two specific positions respectively, (c) causing each of the two point light sources to transmit along corresponding one of predetermined light paths of the image scanning apparatus into the carriage and pass out from the end of the carriage so as to obtain a first set of two projective points at a first distance from one end of the carriage and a second set of two projective points at a second distance from the end of the carriage, (d) obtaining a third projective point lined up with the first set of two projective points by operating the first set of two projective points to develop a first set of three projective points, (e) defining a first set of three calibrating points to be compared to the first set of three projective points, (f) obtaining another third projective point lined up with the second set of two projective points by operating the second set of two projective points to develop a second set of three projective points, (g) defining a second set of three calibrating points to be compared to the second set of three projective points, and (h) adjusting an angle and a position of the reflective lens on the carriage for matching each of the projective points with a corresponding one of the calibrating points so as to achieve a calibrating function.
In a preferred embodiment, the two specific positions are located over which an image sensing device of the image scanning apparatus is to travel.
In another preferred embodiment, the two specific positions are located to which the light paths of the image scanning apparatus are to extend.
Preferably, the end of the carriage is provided for accommodating an object to be scanned.
Preferably, the third projective point of the first set of three projective points is obtained by an extrapolation.
Preferably, the third projective point of the first set of three projective points is obtained by an interpolation.
Preferably, the third projective point of the second set of three projective points is obtained by an extrapolation.
Preferably, the third projective point of the second set of three projective points is obtained by an interpolation.
Preferably, the two point light sources are laser light sources.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which: